Subject: Re: [vserver] Problem with bind mount
From: Erdem Bayer <ebayer@bayer.gen.tr>
Date: Wed, 19 Aug 2009 14:00:44 +0300

Hi

Is it safe to do the bind mounts from the host? What are the pros and cons?

Kind Regards
Erdem Bayer

On Wed, 19 Aug 2009 06:51:24 -0400
"John A. Sullivan III" <jsullivan@opensourcedevel.com> wrote:

> On Wed, 2009-08-19 at 13:23 +0300, Erdem Bayer wrote:
> > Hi
> > 
> > I have a debian lenny i386 vserver running on lenny amd64 host with the following
fstab entry:
> > 
> > none    /proc           proc    defaults                0 0
> > none    /tmp            tmpfs   size=256m,mode=1777     0 0
> > none    /dev/pts        devpts  gid=5,mode=620          0 0
> > /home   /home   bind    bind    0       0
> > /iscsi/www /var/www bind bind 0 0
> > /iscsi/log/concero /var/log bind bind 0 0
> > 
> > When I start a vserver, I see these errors in the output:
> > 
> > secure-mount: mount(): Invalid argument
> > /etc/vservers/concero/fstab:5:1: failed to mount fstab-entry
> > secure-mount: mount(): Invalid argument
> > /etc/vservers/concero/fstab:6:1: failed to mount fstab-entry
> > 
> > But the vserver starts and the directories in fstab file are mounted anyway.
> > 
> > I don't know if it makes a difference but /home fs is ext3, /iscsi is formatted
with ocfs2 and mounted with iscsi. I can mount them manually with the following command:
> > 
> > sudo mount --bind /iscsi/log/concero /etc/vservers/concero/vdir/var/log
> > 
> > When I dig deeper I found that secure-mount is called with the following parameters:
> > 
> > ++ pushd /etc/vservers/concero/vdir
> > ++ test -w etc -o -w etc/mtab
> > ++ /usr/lib/util-vserver/secure-mount -a --chroot --fstab /etc/vservers/concero/fstab
--rootfs no
> > 
> > Here are the strace of the manual running of secure-mount (if it helps):
> > 
> > 
> > chroot(".")                             = 0
> > chdir("/")                              = 0
> > fchdir(3)                               = 0
> > chroot(".")                             = 0
> > chdir("/var/www")                       = 0
> > open(".", O_RDONLY|O_DIRECTORY)         = 6
> > fchdir(4)                               = 0
> > chroot(".")                             = 0
> > fchdir(6)                               = 0
> > close(6)                                = 0
> > mount("/iscsi/www", ".", 0x7fffdf03e67f, MS_NODEV|MS_BIND, 0x7f9ad703f070) = 0
> > fchdir(3)                               = 0
> > chroot(".")                             = 0
> > chdir("/var/www")                       = 0
> > open(".", O_RDONLY|O_DIRECTORY)         = 6
> > fchdir(4)                               = 0
> > chroot(".")                             = 0
> > fchdir(6)                               = 0
> > close(6)                                = 0
> > mount("/iscsi/www", ".", 0x7fffdf03e67f, MS_NODEV|MS_REMOUNT, NULL) = -1 EINVAL
(Invalid argument)
> > write(2, "secure-mount: mount()"..., 21secure-mount: mount()) = 21
> > write(2, ": "..., 2: )                    = 2
> > write(2, "Invalid argument"..., 16Invalid argument)     = 16
> > write(2, "\n"..., 1
> > )                    = 1
> > write(2, "/etc/vservers/concero/fstab"..., 27/etc/vservers/concero/fstab) = 27
> > write(2, ":5:1"..., 4:5:1)                  = 4
> > write(2, ": failed to mount fstab-entry\n"..., 30: failed to mount fstab-entry
> > ) = 30
> > chdir("/")                              = 0
> > fchdir(3)                               = 0
> > 
> > 
> > chroot(".")                             = 0
> > chdir("/var/log")                       = 0
> > open(".", O_RDONLY|O_DIRECTORY)         = 6
> > fchdir(4)                               = 0
> > chroot(".")                             = 0
> > fchdir(6)                               = 0
> > close(6)                                = 0
> > mount("/iscsi/log/concero", ".", 0x7fffdf03e6a9, MS_NODEV|MS_BIND, 0x7f9ad703f090)
= 0
> > fchdir(3)                               = 0
> > chroot(".")                             = 0
> > chdir("/var/log")                       = 0
> > open(".", O_RDONLY|O_DIRECTORY)         = 6
> > fchdir(4)                               = 0
> > chroot(".")                             = 0
> > fchdir(6)                               = 0
> > close(6)                                = 0
> > mount("/iscsi/log/concero", ".", 0x7fffdf03e6a9, MS_NODEV|MS_REMOUNT, NULL) = -1
EINVAL (Invalid argument)
> > write(2, "secure-mount: mount()"..., 21secure-mount: mount()) = 21
> > write(2, ": "..., 2: )                    = 2
> > write(2, "Invalid argument"..., 16Invalid argument)     = 16
> > write(2, "\n"..., 1
> > )                    = 1
> > write(2, "/etc/vservers/concero/fstab"..., 27/etc/vservers/concero/fstab) = 27
> > write(2, ":6:1"..., 4:6:1)                  = 4
> > write(2, ": failed to mount fstab-entry\n"..., 30: failed to mount fstab-entry
> > ) = 30
> > close(5)                                = 0
> > _exit(0)                                = ?
> > 
> > Kind Regards
> > Erdem Bayer
> Might it be faster and easier to do the bind mounts from the host,
> e.g., 
> /somesource/iscsi/log/concero /vservers/vserver1/var/log bind bind 0 0
> 
> -- 
> John A. Sullivan III
> Open Source Development Corporation
> +1 207-985-7880
> jsullivan@opensourcedevel.com
> 
> http://www.spiritualoutreach.com
> Making Christianity intelligible to secular society
>